Telephone-exchange system



July 2, 1929- v R. L. sToKELY l 1,719,091

TELEPHONE EXCHANGE SYSTEM Filed July 14, 1927 3 Sheets-Sheet lI July 2, 1929. R. L .'s'roKELY TELEPHONE EXCHANGE SYSTEM 5 Sheets-Sheet 2 Filed July 14, 1927 bum.

IU) ILUP IID) IDIIolIl PVM' /N VEN raf? y /A y J70/fa y 5y Arm/wir July 2, '1929. L. STOKELY (i 1,71`,991

TELEPHONE EXCHANGE SYSTEM u Filed Ju1y'14, 1927 s, sheets-sheet :s

Patented July 2, 1929.

UNITED STATES PATENT OFFICE.

RAY Il. STOKELY, 0F FLORAL PARK, LONG ISLAND, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORA- TION OF NEW YORK.

TELEPHONE-'EXCHANGE SYSTEM.

Application led July 1%,n

This invention relates to vtelephone eX- change systems and more particularly to improvements in party line service.

According to this invention, a subscriber on a. non-message rate party line may make a revertive call by set-ting up a connection over automatic switches to seize a revertive ringing device which applies ringing current to the calling line Whereas, when a subscriber on a message rate party line attempts to make a revertivi-i call by setting up a connection to the ringing device, the connection thus established is automatically .released to deleat` the attempt, requiring him to first call the operator.

The drawing consists of three figures, which, when arranged in order, disclose a portion ot a step-by-step automatic system embodying the present invention. Fig. 1 illustrates two party lines and the line iinders for extending them. `Fig. 2 illustrates certain oi the selector switches and an operators position diagran'imatically. This iigure also shows the details ot a message register trunk. Fig. 3 shows a special revertive calling` switch and a revertive signaling mechanism.

lherc an exchange serves a number of party lines, it may often be desifable to equip some oit these lines with message registers for charging calls, While other lines are not so equipped but may be charged on a tlat rate basis. Since each call originating on a hat rate line does not have to be registered, the revcrtive` calls may be made Without the assistance et an operator. On the `message register party lines, however, it is desirable to have the subscriber call an operator when he wishes to make a revertive` call.. In this Way the operator has charge oi the connection and tends to the registri tion ot the call against the proper party.

ln the system illustrated, a non-message rate party line 100 having two substations 101 and '102 terminates in the. bank of the line finder F1, which may be of any well known type such as' a two-movement stepby-step switch.` lhen either party on such a line initiates a call the iinder Fl extends the line over a trunk130 to a first selector S. '.lhe subscriber there-upon controls the selector S and succeeding selectors S2 and S3 to extend his lineto a special revertive calling selecter S41- 'lbc switch S* has access 1927. Serial No. 205,540.

through its terminal bank 316 to a code re- `current to be sent back over the calling line in different code combinations to signal any desired party thereon. The switch St is of the single motioni rotary step-by-step type. `q 1 The message register party line such as the line 103, having substations 104: and 105, terminates in the bank of line inder F2. The switch F2 is of the two-movement stepby-step type having tip and ring brushes 100 and 107 cooperating with the bank 110 oft' tip and ring terminals and also auxiliary brushes 108 and 109 carried by the same shat't an d cooperating with the bank of terminals 111. The switch F2 also has a vertical con'imutator strip 117 and eoacting brush 11S. lThe subscriber ci one oi' these message register party lines on initiating a call sets the finder F2 in motion to extend his line over a. trunk 131 to the iirst selector S1. The trunk 131 leading to the iirst selector is a special message register trunk and is provided with equipment for making a test of the calling line to determine which party initiated the call and for selectively operating the message registers. The switch. S1, shown diagramm'atically, is positioned by the calling subscriber to seize the trunk E223 leading to the operators position in case he is making a revertive call. The operator ascertains the number oi the wanted party and assists in establishing the connection and causes the operation oif the message register, all in the usual and Well known manner.

It the message register' party line subscriber wishes to make a direct connection, he may do so by operating the selector SL to seize a trunk leading to the succeeding selector S2 which may be positioned to extend his line in the proper direction.

Should the subscriber of a message rate party line, such as the line 103, attempt to make a revertive call by extending his line to the special selector SL and seizing the reve'rtive ringing device S5, the circuits are so arranged that as soon as he replaces his receiver on the hook to await the application el? ringing current, the entire connection is automatically released, thus deh-eating the attenrit.

at fief.. led descripta-imi wil-Ii :new hi `initter to position the selectors S2 and S3 to extend the line to the switch'S". The inipulse relay 300 is operatedv in a circuit from v-ground, through its right winding, upper contact of relay"301,thence over the tip side vofthe connection, through the subscribers loop Aand returning over the ring side of the connection through the back contact of rclay301, left Winding of relay 300 toY battery i and ground.y

circuit for slow release relay 304.- Relay switchhook .to await the signaling ofthe` Relay 300 closes an `obvious 304 lat its left contact applies ground to the i sleeve conductor 326.

The calling subscriber now transmits a series-ofimpulses to set the switch S* in such a position: thatthe code signaling device S5 wlillcause the sending of a code identity ingthe called subscribers station 102. On the first opening of the line, relay 300 releases 9 and Ycloses a circuit from ground, through its back contact, inner right contact of `relay 304, closedcontacts of the spring combination 308, winding oftvslow release relay' 305, winding of the stepping magnet 311 tobattery. 'JRelay 305 operates andshifts the stepping circuit so that it now leads through the rfront cont-act and winding of said relay independent of the springs 308 whichlshift?on.the tirstfstep of the selector. The magnet 311 steps the brushes 317 to 32() inclusive of the switch S1. "For each succeeding impulse, the magnet. 311 operates. At vthe endv oi vthe. series the brushes of the switchS*v are positioned on the correspond- Ving seti-of terminals in the bank 316. For

thesake .of description it will be. assumed that thebrusheslhave been driven to the -firstset ofi-terminals. inthe bank.

'Following the last iset of impulses, the calling subscriberl replacesrhis receiver on the called party. Relay 300 releases'in response to the'replacement lof thereceiver and in v doing so completes a circuit from ground .through its left contact,.front contact of relay 304, which remainsenergized 'for an interval, back contact of relay 305, which releases-following the completion of the iinpulse series, contact of relay 306, through brushes 318 and 317 and the connected terminals, contact of relay 302, winding of relay'301 to battery. Relay 301 operates and closes aV substitute holding circuit for relay 304.` Relay 301 also completes a circuit from battery, through the Winding of relay 314,

contact of relay 301, interrupter 310 to ground. v Alt each'closure of the interrupter .ceases its stepping action.

In positions 6 to 9 inclusive ofthe switch S5 a circuit is completed from ground, through the brush 323, brush 319, contact ofi-clay 303, winding of relay 312 to battery. Relay 312 operates and connects the generator 313 in a circuit through the lett winding of relay 306, back contact ot relay 30T, front contact of relay 301, to the tip side of the calling line. The ring .side of the line is connected through the contact ot relay 301 and the inner back contact of relay 30T to ground. Current from the generator 3l3 operates the call bells connected to the tip side of the line for an interval measured hy the time required by the switch S5 to pass through two positions. In positions 8 and 9 ofthe switch S5 a circuit is completed troni ground, through the brush 321, thence over brush 320, contact of relay 303, winding of relay 307 t-o battery. Relay 30T shifts the circuit of the generator to the ring side of the line and shifts the ground connection to the tip side. This causes the bells on the other side of the line to ring 'for an interval equivalent to two positions of the switch S.

In position 10 of the switch S5 the pick-up conductor 327 is again grounded, hut since the -relay 303 has already operated nothing happens at this time. In positions 11 to l-t inclusive signals of the saine code are applied to the party line. By means of this code the calling subscriber-s hell is rung for an interval of time following which the called subscribc1"s bell is rung for an equal interval. It will be obvious by inspecting the connections of the switch S that other codes may be obtained by positioning the switch SL at ditfercnt points in its contact bank.

f VWhen the called party answers, the ringing trip relay 306 operates and locks through its right winding to the contact of relay 301.

Relay 306 releases the relay 301 which disconnects the ringing circuit and reconnects the relay 300 to the calling line. Relay 300 operates reclosing the circuit of relay 301; which holds the connection. Relays 303, 312 and 307 are released und the switch S Talking current is fed to the party line through the windv ings ofthe relay 300.

lAtt the end of the conversation the parties iltl loo

lltl

replace their receivers releasing the relay at station 10/1 on the party line 103 makes.

a revertive call by dialing the proper number to extendL his line to the operators position O. On removing his receiver from the sivitclihoolr, the calling subscriber completes a circuit from battery, tlirough the right winding ot relay 112, contact of relay 113, thence over the loop o1 the line and returning to the lett Winding of relay 112. Relay 112 closes an obvious circuit for the group relay 121. Relay 121 places ground poten tial on the group segment and also on `the start Wire 132 completing a circuit through the normal contact o'l relay 120, closed contact o1 the spring combination 126, winding o1 the slow release relay 119 to battery.v Relay 119 closes a circuit for relay 122 traceable from battery, through the otuer lett contact of relay 120, right Winding et relay 122, left contact ot magnet 126, cont-act ot magnet 125, conductor 133 to ground at the outer contact ot' relay 119. Relay 122 closes a circuit as follows ttor the vertical magnet 125: battery, through the outer contact otrelay 120, Winding ot' magnet 125, right back contact of relay 140, contact of relay 122 to ground at the contact oit relay 119. The magnet 125 steps the brushes 106 to 109 inclusive up to the tiret level of contacts. lllagnet 125 opens the circuit oit relay 122 Whichreleases and opens the circuit et the magnet. The magnet in turn releases and recloses the circuit and relay. This action continues until thc ln'ushes reach the level containing the calling subscriber"s line` 103. At this time a circuit is closed from battery, through the right Winding oi relay 122, contact ot' 1nagnet 126, left Winding olf slow relay 1410, brush 118 to the grounded segment 129. Relay 122 operates and holds the circuit of magnet 125 closed to prevent further step- ',ng ot the switch. Relay 140 operates and in a circuit from battery, through the winding of magnet 125, right Winding and contact ot relay 140 to ground at the contact o1 relay 119.

Relay 1110 also closes a circuit :tor the rotary stepping magnet 126 traceable` from l battery, through the Winding of said magnot, front contact of relay 1110, Contact of relay 122 to ground at ,the contact of relay 11.0. The magnet 126 rotates thebrushes on sleeve conductor 136.

the first set of terminals `in the contact banks. lllagnet 126 opens the circuit of relay 122 which releases in turn releasing the circuit and the magnet. This interrupting action continues until the brushes reach the terminals ot the calling line 103. Art this time a circuit is completed from battery through the winding of relay 113` and register 1141- in parallel, contact olf relay 112, thence over the test brush 103, upper winding o1 relay 116, back cont-act ot relay 120, le'lt winding el relay 122 to ground. Relay 116 operates and relay 122 remains energized, but the relay 113 and register lleido not operate in this circuit. Relay 122 by remaining energized prevents lurther stepping ot the switch. Relay 116 completes an operating circuit for relay 120 `trom battery, through the lett winding of the latter relay, front contact oi relay 116, conductor to ground at the contacts el spring combi.- .nation 127. Relay 1.20 in operating shifts the start Wire 132 to the out 'art conductor 135 and opens the circuit olf slow-release relay 110. At the time relay 116 operates it locks temporarily in a circuit from battery, through its lower winding and contact, iti-ont cont-act of magnet 126 to ground at the contact of relay 11). Betere relay 119` deenergizes following the opening olf its circuit, a substitute holding circuit for relay 116 is closed from battery, through the Winding and Contact ont the latter4 relay, inner lett front contact ot' relay 120 to ground on the rlhe manner in which ground is placed on this conductor Will be described presently. rThe release of relay 119 opens the circuit of relays122 and 110. lllhen ground potential is applied to the sleeve conductor 136 the cut olli' relay 113 operates in a circuit 'from battery, through its Winding, right contact olli relay 112, linfush 108, contactol'i relay 116, to condiuztor 136 through the front contact of relay 120. Rclay 1.13 releases the line relay 112.

As soon as relay 1.16 operates, the tip and ring conductors olf the calling line are extended over the truinlr. 131 to operate the impulse relay 206. rllhe circuit for relay 206 leads through the brush 201, over the ring side ol.` the connection and returning through 'the brush 200 to ground through the impedance 20'?. Relay 206 in operating completes a circuit 'lior the impulse relay at the selector' switch Sl. This circuit extends over the ring side oi the connection to the right nf'iruling ol polarized relay 2141;, contact et relay 206, 'winding of relay 210, upper baclr (.contact o1 relay 209, lett winding oit relay 2141, thence over the tip side oii` the trunk to the switch Sl. Relay 210 operates, closing an obvious circuit for slow-operate relay 211. Relay 211 'in turn closes an obvious circuit for relay 200. lhe

flow et current in. the circuit above traced lll) is insuch a direction as not tov operate the relay '214. Y Y

' Inthewell known manner, ground potential is placedon the sleeve conductor 224L as soon as the selector S1 lis seized. r1`his causes the operation of relay 216. Relay Y 216 completes a circuit from ground, through the impedance 220, front contact of relay tery." Magnetv 221advances the 'brushes 200' 216, through vthe sleeve conductor 136 leading back to the line vfinder switch F2. Relay 216 also closes a circuit from ground, through its outer right contact, brush 203, contact and winding. of magnet 221 to batto 205 inclusive to their second position terminals. l

In position 2 of the control switchslowoperate relay 218v is energized in a circuit from battery, through its winding, resistance 222 to ground at the brush 202. Relay 218 closes an obvious circuit for slow-release relay 219. Relay 219 completes a circuit from ground, through the front contact of relay 218, inner lett contactvotl relay 219,

normal contact of slow-release relay 212,

Y conductor 225, brush 203, Contact of winding of magnet 221V to battery.

1\1agnet 221 interrupts itsV circuit 'and steps the switch finto position 3, releasing relays 218 and 219.

vThe switch stays in this position during the dialing by the calling subscriber.

The calling subscriber manipulates his dial to transmitthe digit impulses, releasing and operating in succession the impulse relay 206. On the first release of relay 206,

relay 211 releases` in turn releasing relay` 209. Since relay 211 is slow to operate it Vdoes not attract its armature during the sending of impulses. Relay 206 in releasing opens the circuit leading to the switch ,S1 thus repeating the impulses to said switch tov causeV its operation. The switch Y S1 is thus positioned to seize the trunk 223 leading to the operators position O. The operator answers the call and ascertains the number ot the wanted party. In any well known manner she may apply ringing current to the line toy signal the wanted party and when conversation commences or at any suitable time, she may cause the reversal o1 current to operate the polarizedV relay tery, through the winding of relay 213, front Contact of relay 212, back contact of relay 219 to` ground Vat thefront contact of relay 217. .Relay 2l3closes a circuit from ground,

.shunts the relay 212.

through its outer left contact, conductor 228, through the brush 203 to the stepping magnet 221 to advance the switch into position 4. In position 4 a. circuit is closed from ground, through the front Contact of relay 217, left back contact of relay 219, brush 203 to the magnet 221 advancing the switch into position 5. In position 5 the original circuit of relay 206 is opened butI the relay is now held over a circuit. from battery, through its winding, resistance 226, conductor 227, inner left front contact of relay 216, to ground at the brush 205.

The switch is advanced to position 6 by means ot a circuit from ground, through the right :trent contact of relay 217, back contact ot relay 219,1ront contact of relay 212, brush 203, to the magnet 221. In position 6 the relay 217 releases in turn opening the original circuit of relay 212. Relay 212, however, is held in a circuit from battery, through its winding and front contact, to ground at the brush 202. When relay 217 closes its right back contact, it completes a circuit tor driving the switch from position 6 into position 9.

While the switch is passing through positions 6, 7 and 8 a test is made of' the calling line to determine which party has initiatedthe call. It will be assumed that the station 10,1 in calling applies an identifying ground potential to the tip and ring conductors oi the line. The manner in which a test ot this kind is performed is explained and described in detail in the patent to Taggart et al., 1,513,351, granted )ctober 28, 1924.

lVith the control switch passing through positions 6, 7 and 8, a test circuit is connpleted from battery, through the winding of' relay 218, thence in parallel through the brushes 201 and 200 to the two sides of the subscribers line to ground at thev substation 101. VRelay-218 operates and closes au operating circuit Afor relay 219. Relay 219 locks in a circuit from battery, through its inner lett contact to ground at thel brush 202. lVhen the control switch reaches position 9 relay 218 releases. The switch is driven out of positions 9 and 10 and into position 11 by means oit a circuit it'rom lmttery, through the. winding and contact ot magnet 221, brush 203, conductor 228, 'front contact ot relay 212, to ground at the brush 202. In position 11 a circuit is closed from battery, through the resistance 242, inner right contact of relay 213,. brush 205 to ground. This circuit Relay 2|2 in releasingcompletes a holding circuit for wlay 213 traceable .trom battery, through the winding of the latter relay, normal contacts of relay 212 to ground at the brush 202. In position 11 conversation takes place. In this position relay 206 releases. The tip conductor of the calling line is extended through the brush 200, thence over conductor 230, front Contact o1 relay 216, through the winding ot .relay 2111, to the selector switch S1. The ring conductor is likewise extended through the brush 201, coluluctcr 231, contact et relay 216, to the selector switch S1.

At the end ot conversation the selector S1 is releaseril, reinoving ground potential from conductor 224 to permit the release of relay 210. ,telay 216 advanc s the control. switch into position 12 by means ot' a circuit from rrminrh through its outer right back con tact, lett back contact of relay 217, and the brush 203. The control switch y advances il'rom position 12 to position 18 by means of an nbvious circuit. During these positions, the test relay 218 is again connected to the tip and ring conductors of the calling line to determine it the ground potential has been removed as it should be, or whether the ground potential first encountered was due to an unstandard condition. The circuit for relay 213l may be traced frombattery, through `means et a circuit trom magnet 221, through the brush 203, conductor 33 to the inter rupter 235. In position 20, theswitch is advanced by means ot' a circuit from the magnet 221, tllrough the brush 203, `conductor 234: and interrupter 230. The switch remains in position 21 until the interriuater 235 again closes. lin this position the calling subscribers message register 115 is operated. The circuit may be traced from the positive pole ot booster battery, through the lamp 215, resistance 237, ,trout contact oli relay 213, brush 204, outer right liront contact .et relay 219, conductor 233, front contact of relay 11G, brusa 109, and thence through the register 115 to the negative pole ot battery and ground. When the interrnptcr 235 again closes, the control. switch advances out ot position 21 into position 22 'from whence it is moved into its normal position over an obvious circuit including the brush 203.

The removal of ground potential from the conductor 136 permits the relay 116 to release. Relay 116 completes a circuit :from battery, through the release magnet 124, closed contacts ot the spring combination 127, contact ol relay 14h), back contact of relay 110, lett back contact ot relay 119 to the grounded conductor 1341-.. Magnet 124 releases the finder ll2 opening the holding circuit oit relay 120.

lt will next be assumed that the calling party on the line 103 attempts to make a revertive call by setting up a connection to the ringing device The operation oit the line linder l and of the selectors S1, Sil and S3 takes place as already described to extend the calling line to the special selector St. The switch S4' responds to the impulses dialed and positions its brushes on the selected set oil. terminals in the bank 310. As soon as the calling party hangs up his receiver to await the signaling of the called subscriber, a circuit is completed from ground, through the back contact ot relay 300, inner front contact of relay 301, back Contact oit relay 305, lett Contact ot relay 306, brushes 318 and 317 and the connected terminals, winding oit relay 302, through the brushes oit selectors S5 S2 and S" conductor 2110, conductor 228,*brush 203, Contact and winding of the magnet 221 to battery. It will be recalled that the control switch in Fig. 2 is standing in position 3 at this time. The relay 302 operates in this circuit and prevents the operation ot relay 301. Since the relay 300 is deenergized and since. relay 301 does not operate, relay 3011 releases after an interval. Relay -1 in releasing closes the circuit of the release magnet 309 to restore the switch St. Relay 3011 in removing ground potential from the sleeve conductor 320 causes the release oi? switches S, S: and S1 and the deenergization of relay 216. Relay`216 closes a circuit through the con* tact of relay 217 for driving the control switch out ot position 3 and into position el. From position 4 the switchis driven through succeeding positions over circuitssimilar to those already describedinto its normal position. The line finder sivitch S2 is also released in the manner described. Thus the attempt on the part ot the sulgiscriher ot a message register party line to make a revertive call, without the assistance of the operator, is defeated.

The switches disclosed in this system. are of Athe step-by-step type. The line iiuder F2 is similar to the one disclosed and described in the patent to Carpenter No. 1,567,240, granted December 29, 1925, with certain modifications.

What is claimed is:

1. In a telephone system, lines o1 different classes, a plurality of automatic switches, a revertive calling device, means tor setting said switches to extend any one oit said lines to the revertive calling device, and means responsive to the extension ot lines of a certain class to such device Yfor automatically releasing the connection.

2. In combination, a number of party lines, automatic switches, a.revertive calling device, means controlled by certain oil said lines tor extending such lines over said switches to said device to make revertive calls, and means etlcctive in response'to the extension ot other of said lines to said de vice for automatically releasing the connection.

3. In combination', a number of party lines, automatic switches, a revertive calling device, means for operating said switches to extend any of said lines to the mechanism forrendering it elfective to operate .ther ringers of such line, and means responsive to the extension of another line to` said mechanism for releasing vthe connection.

5. In a telephone system, a plurality of party lines, selector switches, a signaling device, an operators position, means controlled by a subscriber of one of said lines for setting said switches to extend his line to said signaling device, means operated by said device for signaling the parties of said lastY mentioned line, means controlled by a party on another line vfor setting said switches to extend his line either to the operators position or to f said device, and

means responsive to the extension of said last line to the signaling device for releasing the connection.

6. In combination, a number of party lines, a revertive ringin device, a selector switch, means for exten( ing said lines over separate paths to said selector, mcans for operating the selector from either line to seize said ringing device, said device serving to signal the subscribers on a calling party line, and means in the path over which one of said lines is extended for effecting the release of the connection responsive to the seizure of said ringing device.

7. In combination, party lines equipped with message registers, party lines not equipped with message registers, a revertive ringing device, selector' switches operable to extend any one of said lines to the ringing device, said device serving to send ringing current over a non-message register calling party line, and means responsive to the cxtension of a message register line to said dcvice for automatically releasing the conncc tion.

8. In a telephone sistem, two different party lines, a series o selector switches, a revertive calling mechanism, means for setting said switches to extend either of said. lines to the calling mechanism, ringcrs at the substations of said lines, means responsive to the extension of one of said lilies to said mechanism and controlled by the calling partys switchhook for renderingr said mechanism effective to operate the ringers of such line, and means responsive tothe connection of the other line to said mechanism and controlled by the calling partys switchhook for releasing the connection.

In Witness whereof', I hereunto subscribe my name this 12th day of July, A. D. 1927.

RAY L. STOKELY. 

